HighGHSA-77mr-wc79-m8j3BIT-phpmailer-2021-3603CVE-2021-3603

PHPMailer untrusted code may be run from an overridden address validator

Published 22 Jun 2021 · Updated 17 Feb 2024

Affected package

phpmailer/phpmailerComposer
Affected
<6.5.0
Fixed in
6.5.0
Update to the fixed version for your release line, for example:composer require phpmailer/phpmailer:^6.5.0

Details

If a function is defined that has the same name as the default built-in email address validation scheme (php), it will be called in default configuration as when no validation scheme is provided, the default scheme's callable php was being called. If an attacker is able to inject such a function into the application (a much bigger issue), it will be called whenever an email address is validated, such as when calling validateAddress().

Impact

Low impact – exploitation requires that an attacker can already inject code into an application, but it provides a trigger pathway.

Patches

This is patched in PHPMailer 6.5.0 by denying the use of simple strings as validator function names, which is a very minor BC break.

Workarounds

Inject your own email validator function.

References

Reported by [Vikrant Singh Chauhan](mailto:vi@hackberry.xyz) via huntr.dev. CVE-2021-3603

For more information

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References

Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.